Just thought I would pass on a bit of data. There are several firewall distributions out there in the net. Many of them are really good. Some are better than others. One that you I have not seen much of is actually my current favorite. Endian Firewall. This is a feature rich firewall distribution that does a lot and offers control over more than most of the others you can get for free.
Main things I like that it has from the start is outbound firewall control, application-level proxies for various protocols (HTTP, FTP, POP3, SMTP) with antivirus support, virus and spam filtering for email traffic (POP and SMTP), content filtering of Web traffic. The feature list is rather nice.
If you are looking into a firewall solution check it out.
Link : Endian Firewall Community